Stability of La–Sr–Co–Fe Oxide–Carbonate Dual-Phase Membranes for Carbon Dioxide Separation at High Temperatures

W-doped Lanthanum Molybdenum Oxide/Lithium-Sodium-Potassium Carbonate Composite Membranes for Carbon Dioxide Permeation

Single-phase tungsten-doped lanthanum molybdenum oxide (La₂MoWO₉) ceramic powders were synthesized using the complex polymerization technique. Porous ceramic pellets were obtained by thermally removing graphite, which served as a pore former. The porous pellets were then impregnated with molten eutectic lithium-sodium-potassium carbonates. The energy dispersive X-ray analysis and scanning electron microscopy (FEG-SEM) images of the external and fracture surfaces of the La₂MoWO₉-(Li,Na,K)₂CO₃ composite dual-phase membrane revealed the percolation of the carbonate mixture through the pores. Electrochemical impedance spectroscopy measurements conducted at temperatures below and above the melting point of the eutectic carbonate composition demonstrated the contributions of oxygen and carbonate ions to the ionic conductivity of the dual membrane. The electrical conductivity of the carbonate ions within the membrane was continuously monitored for over 1300 h with negligible degradation, implying that the membrane could be used for long-term monitoring of CO₂ without aging effects. A comparison of FEG-SEM images taken before and after this endurance test suggested minimal fouling, indicating that the membrane could potentially replace similar zirconia- and ceria-based composite membranes.

Recent Advances in Molten-Carbonate Membranes for Carbon Dioxide Separation: Focus on Material Selection, Geometry, and Surface Modification

Membranes for carbon dioxide permeation have been recognized as potential candidates for CO₂ separation technology, particularly in the energy sector. Supported molten-salt membranes provide ionic routes to facilitate carbon dioxide transport across the membrane, permit the use of membrane at higher temperature, and offer selectivity based on ionic affinity of targeted compound. In this review, molten-carbonate ceramic membranes have been evaluated for CO₂ separation. Various research studies regarding mechanisms of permeation, properties of molten salt, significance of material selection, geometry of support materials, and surface modifications have been assessed with reference to membrane stabilities and operational flux rates. In addition, the outcomes of permeation experiments, stability tests, selection of the compatible materials, and the role of interfacial reactions for membrane degradation have also been discussed. At the end, major challenges and possible solutions are highlighted along with future recommendations for fabricating efficient carbon dioxide separation membranes.

Catalytic mixed conducting ceramic membrane reactors for methane conversion

Schematic of catalytic mixed conducting ceramic membrane reactors for various reactions: (a) O₂ permeable ceramic membrane reactor; (b) H₂ permeable ceramic membrane reactor; (c) CO₂ permeable ceramic membrane reactor.

Ceria-Based Dual-Phase Membranes for High-Temperature Carbon Dioxide Separation: Effect of Iron Doping and Pore Generation with MgO Template

Dual-phase membranes for high-temperature carbon dioxide separation have emerged as promising technology to mitigate anthropogenic greenhouse gases emissions, especially as a pre- and post-combustion separation technique in coal burning power plants. To implement these membranes industrially, the carbon dioxide permeability must be improved. In this study, Ce_0.8Sm_0.2O_2-δ (SDC) and Ce_0.8Sm_0.19Fe_0.01O_2-δ (FSDC) ceramic powders were used to form the skeleton in dual-phase membranes. The use of MgO as an environmentally friendly pore generator allows control over the membrane porosity and microstructure in order to compare the effect of the membrane's ceramic phase. The ceramic powders and the resulting membranes were characterized using ICP-OES, HSM, gravimetric analysis, SEM/EDX, and XRD, and the carbon dioxide flux density was quantified using a high-temperature membrane permeation setup. The carbon dioxide permeability slightly increases with the addition of iron in the FSDC membranes compared to the SDC membranes mainly due to the reported scavenging effect of iron with the siliceous impurities, with an additional potential contribution of an increased crystallite size due to viscous flow sintering. The increased permeability of the FSDC system and the proper microstructure control by MgO can be further extended to optimize carbon dioxide permeability in this membrane system.

The effect of microstructure and surface decoration with K2NiF4-type oxide upon the oxygen permeability of perovskite-type La0.7Sr0.3FeO3−δ hollow fiber membranes

Dense La_0.7Sr_0.3FeO_3−δ (LSF) hollow fiber membranes with two kinds of microstructures (LSF-a and LSF-b) were prepared by the phase inversion/sintering method, and the outside surfaces were modified with K₂NiF₄-type oxide in discontinuous method.